This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A057149 #7 May 24 2022 18:49:24 %S A057149 0,1,0,0,1,1,1,0,0,0,1,2,5,4,3,1,1,0,0,0,0,1,2,11,21,34,33,33,19,14,6, %T A057149 3,1,1,0,0,0,0,0,1,2,14,49,131,248,410,531,601,566,474,336,222,124,67, %U A057149 32,16,6,3,1,1,0,0,0,0,0,0,1,2,15,69,288,840,2144,4488,8317,13160 %N A057149 Triangle T(n,k) of n X n binary matrices with k ones, with no zero rows or columns, up to row and column permutation. %C A057149 Row sums give A054976. %H A057149 Sean A. Irvine, <a href="/A057149/b057149.txt">Table of n, a(n) for n = 1..1029</a> %H A057149 Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a057/A057149.java">Java program</a> (github) %e A057149 [0,1], [0,0,1,1,1], [0,0,0,1,2,5,4,3,1,1],...; %e A057149 T(4,6)=11, i.e. there are 11 4 X 4 binary matrices with 6 ones, with no zero rows or columns, up to row and column permutation: %e A057149 [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1] %e A057149 [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 1 0] %e A057149 [0 0 0 1] [0 0 1 0] [0 0 1 0] [0 0 1 1] [0 1 1 0] [0 0 1 1] %e A057149 [1 1 1 0] [1 1 0 1] [1 1 1 0] [1 1 0 0] [1 0 1 0] [1 1 0 0] %e A057149 and %e A057149 [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1] [0 0 0 1] %e A057149 [0 0 1 0] [0 0 1 0] [0 0 1 0] [0 0 1 0] [0 0 1 0] %e A057149 [0 1 0 0] [0 1 0 1] [0 1 0 1] [0 1 0 1] [1 1 0 0] %e A057149 [1 0 1 1] [1 0 0 1] [1 0 1 0] [1 1 0 0] [1 1 0 0]. %Y A057149 Cf. A056080, A056037, A056079, A057150-A057152, A049311. %K A057149 nonn,tabf %O A057149 1,12 %A A057149 _Vladeta Jovovic_, Aug 14 2000